BUG/MEDIUM: ssl-gencert: Unlock LRU cache if failing to generate certificate

In ssl_sock_generate_certificate(), if the LRU cache for generated
certificates is used, the LRU tree is not unlocked on cache miss if the
certificate generation failed. So let's unlock it on error path.

The bug was introduced by the commit fbc98eb ("BUG/MEDIUM: ssl: fix error
path on generate-certificates"). So this patch must be backported with the
commit above, so to all stable versions.

Author: capflam

src/ssl_gencert.c

@@ -356,8 +356,10 @@ int ssl_sock_generate_certificate(const char *servername, struct bind_conf *bind
 			ssl_ctx = (SSL_CTX *)lru->data;
 		if (!ssl_ctx && lru) {
 			ssl_ctx = ssl_sock_do_create_cert(servername, bind_conf, ssl);
-			if (!ssl_ctx)
+			if (!ssl_ctx) {
+				HA_RWLOCK_WRUNLOCK(SSL_GEN_CERTS_LOCK, &ssl_ctx_lru_rwlock);
 				goto error;
+			}
 			lru64_commit(lru, ssl_ctx, cacert, 0, (void (*)(void *))SSL_CTX_free);
 		}
 		SSL_set_SSL_CTX(ssl, ssl_ctx);